Switching elements of this kind are utilized whenever it is desired in a relatively simple way to regulate a temperature around a setpoint which cannot be adjusted by the user, and thus is prescribed by the mechanism, or to accomplish a temperature limitation. Typical areas of application for such thermically controlled electrical switching elements are household appliances, such as electric cooking pots, friers, hairdriers, irons (simple irons without user-adjustable temperature), and the like. The essential elements of switching elements of this kind are a bimetallic spring plate and a switch contact which can be connected into the current path of a heating element, which are arranged together in or on a socket. The bimetallic spring plate is supported at its periphery in such a way that above a transition temperature it can deflect in a first direction A, and below a second transition temperature, it can deflect in a second direction B. The moving part of the switch contact is coupled to the spring movement of the center of the bimetallic spring plate through a control element (such as an axially displaceable pin), in such a way that upon deflection of the bimetallic spring plate in one of the directions (for example A), the contact is opened.
Together with the bimetallic spring plate is installed another steel plate, that with deflection of the bimetallic spring plate in the first direction, is also movable or deflectable in this first direction. The control element engages it at the center, and, depending upon the position of the spring plate, opens the switch contact.
From U.S. Pat. No. 4,053,859, for example, a temperature limiter is known, in which after accomplishment of thermic disconnection of the switch element, the switch contacts can be reclosed manually, by pressing a pin extending axially. lf there is to be provision for manually shutting off the device equipped with this switching element, an additional, external switch must be installed in the current path.